Which of the following is the structure designed to verify and authenticate the identity of...

A public key infrastructure (PKI) is a set of roles, policies, and procedures needed to create, manage, distribute, use, store, and revoke digital certificates [1] and manage public-key encryption. The purpose of a PKI is to facilitate the secure electronic transfer of information for a range of network activities such as e-commerce, internet banking and confidential email.

References: https://en.wikipedia.org/wiki/Public_key_infrastructure